Antipyrine and pyridine n-oxide complexes of iron(II)

Iron(II) complexes of 1-phenyl-2,3-dimethyl-5-pyrazolone (antipyrine, Apy) and pyridine N-oxide (PyO), having the formulae [Fe(Apy)6](ClO4)2, Fe(Apy)2Cl2, Fe(Apy)2Br2, Fe(Apy)4I2, [Fe(PyO)3Cl3]2 . 2H2O, [Fe(PyO)Cl2 . 2H2O]2, [Fe(PyO)3Br2]2 and [Fe(PyO)6]I2 have been prepared and characterized. [Fe(Apy)6](ClO4)2 in nitrobenzene and [Fe(PyO)6]I2 in acetonitrile behave as 1:2 electrolytes; Fe(Apy)4I2 shows considerable dissociation while Fe(Apy)2Cl2 and Fe(Apy)2Br2 are non-electrolytes and monomeric in nitrobenzene. [Fe(PyO)3Cl2]2 . 2H2O and [Fe(PyO)3Br2]2 in nitrobenzene and [Fe(PyO)Cl2 . 2H2O]2 in acetonitrile behave as non-electrolytes. All the complexes are spin-free. The i.r. spectra show that the oxygens of the CO and NO groups are the donors in the Apy and PyO complexes. A large decrease in the NO stretching frequency in [Fe(PyO)Cl2. 2H2O]2 suggests PyO acts as a bridge forming a binuclear complex. The chloro and the bromo complexes of Apy have been assigned pseudo tetrahedral structures while the rest of the complexes have octahedral or near octahedral configurations around the iron(II) on the basis of the magnetic moments and the electronic transitions.

4,4′-Bipyridyl complexes of iron: Magnetic, Mössbauer and other spectroscopic studies

4,4prime-Bipyridyl (4,4prime-bipy) complexes of ferrous salts of the Fe(4,4prime-bipy)x(anion)y type (where x or y=1 or 2) and of ferric salts of the Fe(4,4prime-bipy)m(anion)n type (where m=1 or 2 and n=3) have been synthesised. Elemental analyses, i.r. and electronic spectra, magnetic and Mössbauer studies have been performed to characterize the complexes. 4,4prime-Bipy and some anions are inferred to act as bridging ligands. The magnetic moments, electronic and Mössbauer spectra suggest that the complexes are of high spin type with distorted octahedral structures. The value of the isomer shift and quadrupole splitting are discussed in terms of bonding of the ligand and anions.

Solution conformation of a tetradecapeptide stabilized by two di-n-propyl glycine residues

The solution conformation of a designed tetradecapeptide Boc-Val-Ala-Leu-Dpg-Val-Ala-Leu-Val-Ala-Leu-Dpg-Val-Ala-Leu-OMe (Dpg-14) containing two di-n-propyl glycine (Dpg) residues has been investigated by H-1 NMR and circular dichroism in organic solvents. The peptide aggregates formed at a concentration of 3 mm in the apolar solvent CDCl3 were broken by the addition of 12% v/v of the more polar solvent DMSO-d(6). Successive NiH <-> Ni+1H NOEs observed over the entire length of the sequence in this solvent mixture together with the observation of several characteristic medium-range NOEs support a major population of continuous helical conformations for Dpg-14. Majority of the observed coupling constants ((3)(alpha)(JNHC)(H)) also support phi values in the helical conformation. Circular dichroism spectra recorded in methanol and propan-2-ol give further support in favor of helical conformation for Dpg-14 and the stability of the helix at higher temperature. Copyright (C) 2010 European Peptide Society and John Wiley & Sons, Ltd.

Biosorption of iron(III) from aqueous solutions using the husk of Cicer arientinum

Iron is a major pollutant released as a by-product during several industrial operations especially during acid mining of metal ores. In this paper, the use of Bengal gram husk (husk of channa dal, Cicer arientinum) in the biosorption of Fe(III) from aqueous solutions is discussed. Parameters like agitation time, adsorbent dosage and pH were studied at different Fe(Ill) concentrations. The adsorption data fit well with Langmuir and Freundlich isotherm models. The adsorption capacity (q(max)) calculated from the Langmuir isotherm was 72.16 mg of Fe(III)/g of the biosorbent at an initial pH of 2.5. Desorption Studies were performed at different concentrations of hydrochloric acid showing that quantitative recovery of the metal ion is possible. The infrared spectra of the biomass before and after treatment with Fe(III), revealed that hydroxyl, carboxyl and amide bonds are involved in the uptake of Fe(III) ions.

Bonding isomerism in the chelate-exchange reactions of isonitroso-β-keto-imino isomeric nickel(ii) mixed ligand complexes

A novel chelate exchange reaction, leading to the formation of a series of N-alkyl substituent dependent mixed ligand isomeric complexes of the type Ni(R-AB)(AC') and Ni(R-AC)(AB') (Figure 1) are discussed. Here, AB and AC denote two different N-bonded isonitroso-β-keto-imino ligand moieties, while AB' and AC' are the corresponding O-bonded ligand moieties and R is an N-alkyl substituent. The isomeric complexes are suggested to be monomeric, neutral and diamagnetic with an asymmetric square planar geometry. The bonding isomerism of the isonitroso group in these complexes is discussed on the basis of the infrared and proton magnetic resonance spectral studies. A probable mechanism for the preparative route is also proposed.

Intermolecular Chelate Linkage Isomerism of the Hydroxyimino Group in the Nickel(II), Copper(II), and Palladium(II) Complexes of Quadridentate Schiff-base Ligands

The C-nitrosation of bivalent quadridentate β-imino ketone complexes of nickel(II), copper(II), and palladium(II), with nitrosating reagents has been investigated. The chemical analysis and spectroscopic results reveal that one of the α-CH groups of the coordinated lignad undergoes selective nitrosation forming mono(hydroxyimino) derivative. The hydroxyimino group introduced coordinates through either N- or O- atom to metal(II) by dislodging the carbonyl group already coordinated. This gives rise to two linkage isomers, one with N-bonded and the other with O-bonded hydroxyimino group in the case of nickel(II) (except for 1d) and palladium(II), and a single isomer with O-bonded hydroxyimino group in copper(II) complexes. The isomers obtained from 1b and 1i have been separated by column chromatography. In chloroform each of the isomers of nickel(II) isomerizes to give an equilibrium mixture of two isomers, but not those of copper(II) and palladium(II).

Charred seeds in Mikkeli Orijärvi : A study of subsistence strategies of an Iron Age settlement in East Finland

In this study the over 350 macrofossil samples, containing over 2300 charred plant remains from an Iron Age settlement containing fossil fields in Mikkeli Orijärvi Kihlinpelto, were studied archaeobotanically. The aim was to get more information about subsistence strategies, especially agriculture and study differences in the plant combinations in the different structures and use the archaeobotanical theory to interpret these structures. The methodological question was to study the taphonomy of the charred plant material. The results gave a diverse impression of the agriculture and subsistence strategies of the settlement in Orijärvi, where barley was the most important cereal with rye, wheat and oat cultivated as minor crops. The arable weed assemblage indicates that the fields were situated in different kinds of soils and the crops were cultivated when different kind of weather conditions were prevailing. Ergot was found with the cereals, and it was growing on some of the arable crops and it also indicates wet climate. Hemp and flax were cultivated and wild plants were collected. The meadow and wetland plants found in the material derive most probably from animal fodder. Tubers of bulbous oat-grass were interesting, because they are usually found in graves. Comparison with other Iron Age settlements and graves indicates that the plant material found from the ancient field layers derives most probably from dwellings and graves, which were taken into cultivation.

Zeta Potential Studies On Some Iron-Ore Minerals In The Presence Of Starches

Authors perform zeta potential studies on hematite, corundum, and quartz samples using starches to understand the adsorption behavior of polymeric starch flocculants at the oxide mineral-solution interface and to correlate this information with their flocculation characteristics and investigate effects of pH and CaCl#72 on zeta potential of Fe ore minerals.

A convenient and high-yield synthesis for pyridinium and metal hexafluorocomplexes of vanadium, chromium, iron and cobalt

Pyridinium poly(hydrogen fluoride) reacts with the oxide of vanadium(V) and chlorides of chromium(III), iron (III) and Co(II) at room temperature forming the pyridinium salts of hexafluoro vanadate(V), hexafluorochromate(III), hexafluoroferrate(III) and hexafluorocobaltate(II) in near quantitative yields (80%). These pyridinium salts are the precursors for the preparation of the alkali metal hexafluorometallates by metathetic reactions in acetonitrile medium with the corresponding metal chlorides. The prepared salts have been identified by their infrared spectral data and elemental analysis.